this is a ambigous question....it depends. Some people just hate vet & mexican gear period. And some say they have a reputation for painful injections. I suppose it depends on the cost/benefits ratio.
Personally, I am using the TT Ox($120) and TT Enth($13) now and like the results. Based on the price and results, I am satisfied with these 2 products. I can't speak for their other injectables, but I think the Test Enth is smooth....no pain or soreness afterwards at all.
And hell, I haven't used it yet but $225 for 500 WinstrolV tabs is a bargain compared to getting Zambon.
In summary, IMO it is "good".